A fluid supply apparatus with a plurality of flow lines branching out from one pressure regulator with the flow lines arranged in parallel and constructed so that opening or closing one flow passage will have no transient effect on the steady flow of the other flow passages. Each flow passage is provided with a time delay-type mass flow controller MFC so that when one closed fluid passage is opened, the mass flow controller on that flow passage reaches a set flow rate Qs in a specific delay time At from the starting point. The invention includes a method and an apparatus in which a plurality of gas types can be controlled in flow rate with high precision by one pressure-type flow control system.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A flow factor-based fluid-switchable pressure flow control method, comprising the steps of: calculating a flow rate Qc of gas passing through an orifice according to the formula Qc KP 1 , wherein K a constant with a pressure P 1 on an upstream side of the orifice set at twice or more higher than a pressure P 2 on a downstream side, wherein a flow factor FF for each kind of gas is calculated as follows: FF ( k/ s ) 2/( 1) 1/( 1) / ( 1) R 1/2 wherein: s concentration of gas in standard state; ratio of specific heat of gas; R constant of gas; and K proportional constant not depending on the type of gas; and when a calculated flow rate of a gas type A is Q A and gas type B is allowed to flow through the same orifice under the same pressure on an upstream side and at the same temperature on the upstream side a flow rate Q B is calculated as follows: Q B ( FF B /FF A ) Q A wherein: FF A flow factor of gas type A, and FF B flow factor of gas type B.
2. A flow factor-based fluid-switchable pressure flow control system, comprising: a control valve for controlling a flow rate of a fluid; an orifice formed downstream of said control valve for discharging fluid; a pressure detector disposed between said control valve and said orifice for detecting a pressure between said control valve and said orifice; and a flow rate setting circuit, wherein a pressure P 1 on an upstream side is held to be about twice or more higher than a downstream pressure P 2 , a flow rate Qc of a specific gas type is calculated as Qc KP 1 , where K is a constant, wherein the control valve is controlled to open or close according to a difference signal between the calculated flow rate Qc and a set flow rate Qs, wherein storage means are provided for storing a flow factor ratio, FF B /FF A , of gas type A to gas type B calculated for each gas as follows: FF ( k/ s ) 2/( 1) 1/( 1) ( / ( 1) R 1/2 wherein: s concentration of gas in standard state ratio of specific heat of gas; R constant of gas; K proportional constant not depending on the type of gas; and further comprising calculation means wherein, if a calculated flow rate of gas type A is Q A , and, when gas type B is allowed to flow through a same orifice under a same pressure on an upstream side and at a same temperature on an upstream side, flow rate Q B for gas type B is calculated as follows: Q B ( FF B /FF A ) Q A
3. A parallel divided flow fluid supply apparatus, comprising: a pressure regulator having an upstream side and a downstream side; a plurality of parallel flow passages disposed downstream of said pressure regulator, wherein a single flow of fluid from said pressure regulator is branched into said parallel flow passages; a plurality of flow control valves disposed in said flow passages; and a plurality of flow factor-based fluid switchable pressure flow control systems for controlling of the flow rate, one controller installed in each flow passage between two of said flow control valves disposed upstream and downstream of said controller respectively; wherein said controller comprises: a control valve for controlling the flow rate of the fluid; an orifice formed downstream of said control valve for discharging the fluid; a pressure detector disposed between said control valve and said orifice for detecting pressure between said control valve and said orifice; and a flow rate setting circuit, wherein pressure P1 on an upstream side is held to be about twice or more higher than a downstream pressure P2, and the flow rate Q c of a specific gas type can be calculated as Q c KP1, wherein K is a constant, wherein the control valve is controlled to open or close according to a difference signal between a calculated flow rate Q c and a set flow rate Q s , further comprising a storage means for storing a flow factor ratio FF B /FF A of gas type A to gas type B, which is calculated for each type of gas as follows: FF ( k/ s ) 2/( 1) 1/( 1) / ( 1) R 1/2 wherein: s concentration of gas in standard state; ratio of specific heat of gas; R constant of gas; k proportional constant not depending on the type of gas; and further comprising calculation means so that when a calculated flow rate of gas type A is Q A , and, gas type B is allowed to flow through a same orifice under a same pressure on an upstream side and at a same temperature on an upstream side, a flow rate Q B for gas B is calculated as follows: Q B ( FF B /FF A ) Q A .
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
June 6, 2002
November 23, 2004
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